When products are dispensed from a container, such as a bottle, air is entrained into the bottle. The result is a reduced product quality due to oxidation, bacterial contamination, loss of volatiles, and the like. Moreover, dispensing of highly viscous products is challenging for standard containers, and often results in non-dispensed residues. Hence, bag-in-bottle type containers have been developed in order to limit air entrainment into the bottle, and enable dispensing of higher viscosity liquids to virtually the last drop.
Typically, such bag-in-bottle containers comprise an outer bottle and an inner flexible bag. The outer bottle typically includes a resilient side wall portion. When dispensing via squeezing, pumping, and the like, product from the bag is forced through a dispensing passage, as the inner product bag is collapsed under pressure. The inner bag preferably collapses while maintaining a passage for the product contained therein, to the opening, such that product is not trapped in the inner bag, as the inner bag collapses. Typically, this is achieved by connecting the inner bag to a resilient outer bottle with at least one interlock. An interlock is typically located at the bottom of the bottle, in order to avoid product entrapment, but also to hide the interlock and reduce its impact on the aesthetic form of the bottle.
Such bag-in-bottle containers are typically made via stretch blow-moulding of a preform. In order to blow-mould such preforms, the preform is typically heated such that the preform can be formed to the desired shape. However, during the heating and blowing process, the interlock must be kept cold, in order to avoid damage and deformation of the interlock, or even separation of the inner and outer layers at the interlock. For instance, in WO2012/083310 A2, heating elements are positioned in order to heat the preform sides, but not where the valve is positioned. In addition, heat shielding is typically placed around the interlock, or air is blown on the interlock, in order to limit the temperature increase of the interlock. Since the interlock has to be kept cool during the blowing process, such preforms cannot be blown in standard blow-moulding machines, without significant modification to the blow-moulding machine.
Therefore, a need remains for a preform for bag-in-bottle containers, which can be formed into the container without requiring complex processes or machine changes, and to avoid damage to the interlock.
WO2012/083310, U.S. Pat. No. 2,608,320, U.S. Pat. No. 4,842,165 and WO2008129016 disclose bag-in-bottle containers, preforms for making them, and processes for converting such preforms into containers.